This project proposes a detailed, theoretically grounded approach to a common, yet significant, feature of adolescence: the social marginalization of young people who are different. As reflected in many high profile cases in the last decade, adolescents who do not "fit in" at school--in terms of their looks, background, or behavior---can be ostracized, stigmatized, or harassed by their peers and fellow students, and the consequences of this marginalization can be severe for the adolescents themselves, their schools, and the communities in which these dynamics play out. To better understand the mechanisms underlying the short- and long-term consequences of this complex phenomenon, this project will undertake a three-step analysis derived from the theoretical model of the Looking Glass Self: 1) identifying adolescents at risk of social marginalization at school because their economic, academic, and health characteristics are discordant with the average occurrence of these characteristics in the social contexts of their schools, as captured by in-school peer network and the student body as a whole; 2) investigating the association between risk of marginalization and adolescent depression; and 3) examining whether the depression arising from risk of marginalization in adolescence translates into problematic coping behaviors in young adulthood. These steps will be undertaken by applying multi-level modeling techniques to a sample of 8,272 young people from the National Longitudinal Study of Adolescent Health (Add Health). This dataset contains self- and parent-reported data for the measurement of the economic, academic, and health characteristics of adolescents; network data based on the reports of adolescents and their friends that allows the identification and measurement of the characteristics of in-school peer groups; a near-Census of study schools at one data point that can be tapped to create summary statistics for the student body of each school; and a longitudinal framework that allows for temporal ordering among key concepts, the modeling of selection processes into risk of marginalization, and the linkage of adolescence and the transition to young adulthood. This combination of a classic social psychological perspective and nationally representative data on adolescents positions this project to better understand how and why the vulnerability of young people to social marginalization at school can be disruptive to their own development and also translate into greater social problems.